1. Field of the Invention
This invention relates to an image input apparatus for inputting a color image on an original in a digital color copying machine, and more particularly to an image input apparatus having a function of automatically detecting the presence or absence of a specified original and controlling the output format or manner of the input image.
2. Description of the Related Art
Recently, as the digital color copying machine is more widely used and the image quality thereof is further enhanced, the possibility that crimes of forging bills, stocks or bonds are committed becomes higher.
Therefore, as a means for preventing the above crimes, a copying machine is developed which extracts a specified pattern based on an output of image input means such as a line sensor for inputting a color image on an original, detects the presence or absence of a bill or the like in the original by deriving the matching degree between the extracted specified pattern and a preset reference pattern and inhibits or interrupts the copying operation when the presence of the bill or the like is detected.
As a method for detecting a specified object from unspecified objects with high precision by use of a color image, for example, a method disclosed in U.S. patent application Ser. No. 275,441, filed on Jul. 15, 1994 is proposed. This method is to detect a bill or the like by forming a histogram or a frequency distribution pattern based on the color image and comparing the distribution pattern with a reference pattern.
However, in the conventional specified original identifying method, for example, the identifying method for comparing the frequency distribution of the color image with reference data, even a different pattern may sometimes have the same frequency distribution, and in this case, the identification operation will be erroneously effected. Further, storing means not only for the image pattern but also for frequency distribution data is necessary, causing the structure of the apparatus to be made larger.